Individual carbon nanotubes (“CNTs”) are stronger than any other known material. CNTs with perfect atomic structures have a theoretical strength of above 100 GPa. In practice carbon nanotubes do not have perfect structures. CNTs have been prepared with a measured strength of greater than 60 GPa, and the strength may improve upon annealing. For comparison, Kevlar fibers currently used in bullet-proof vests have a strength of about 3 GPa, and carbon fibers used for making space shuttles and other aerospace structures have strengths of about 2-6.9 GPa.
While CNTs are extremely strong materials, current methods for preparing them result in lengths on the order of only a few millimeters. Processing these short CNTs to produce materials with more practical uses is an important challenge. Several approaches for processing CNTs into CNT fiber (sometimes referred to as CNT yarn) have been reported. One approach involves preparing an array of CNTs and dry spinning a fiber from the array. Other approaches involve dispersing CNTs in polymer or acid solutions and then spinning the CNTs into a fiber.